High-temperature flue gas cooling structure with high content of low-melting-point salt and suitable for incinerator

Abstract

The invention relates to a high-temperature flue gas cooling structure with high content of low-melting-point salt for an incinerator. The high-temperature flue gas cooling structure comprises a furnace body cooling area structure, a cooling water spray gun and a combined spray pipe, the structure of the cooling area of the furnace body adopts a cylindrical shrinkage form, and the ratio D / d of the inner diameters before and after shrinkage is 1.25-1.5; the combined spray pipe comprises a plurality of spray pipes which are uniformly distributed in the circumferential direction and located at the upstream 1 / 10 furnace inner diameter D of the structure shrinkage section of the furnace body cooling area; the combined spray pipe converts static pressure of cooling air into dynamic pressure to form annular wall jet flow and eccentric jet flow, the two jet flows are opposite in direction, the annular wall jet flow plays a supporting role on the eccentric jet flow, and meanwhile the annular wall jet flow and the eccentric jet flow interact to generate local vortex to accelerate mixing of flue gas and the cooling air; the cooling water spray gun is used for reducing the flow of cooled smoke and located at the position of the upstream 1 / 2 furnace inner diameter D of the combined spray pipe, the dip angle beta of the spray gun is 5-15 degrees downwards, and the atomization angle of the spray gun ranges from 60 degrees to 75 degrees. The furnace body wall surface is protected, the cooling efficiency is improved, and the effects of rapidly cooling and preventing the furnace body wall surface from salt deposition are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of high-salt-content high-temperature flue gas cooling, and relates to a high-temperature flue gas cooling structure with a high content of low-melting-point salt suitable for an incinerator. Background Art

[0002] At present, the incineration scheme of salt-containing organic waste liquid is mostly adopted for vertical top burning. The high-temperature flue gas (about 1100℃) generated after incineration forms low-melting-point salt at the same time. Compared with the ash of traditional coal-fired boilers, the ash melting point is low (about 650-850℃), and it has extremely strong adhesion in this temperature range. The dust content of the flue gas reaches 20mg / Nm3, which is a flue gas with a high content of low-melting-point salt. In order to ensure that the molten salt passes through the incinerator smoothly, the flue gas needs to be cooled quickly so that the molten salt can quickly pass through the high viscosity temperature range to avoid its adhesion to the inner wall of the incinerator and cause corrosion and adhesion.

[0003] In the early days, JOHN ZINK COMPANY, LLC used water spray cooling to cool salty flue gas. This method resulted in a water content of nearly 40% in the flue gas, which caused the system to become easily clogged after salt discharge. The device could only operate at low load and had a limited operating time.

[0004] Kellert Combustion Technology and Equipment (Shanghai) Cable Company adopts the method of mixing air (or circulating low-temperature flue gas) cooling. The specific method is: a long cooling space is reserved at the bottom of the furnace body, and the cooling air ducts are densely arranged at the same height in a circle, and a low-temperature gas jet is sprayed to the center of the furnace body. This method can effectively protect the wall surface, but the jet wind intensity is limited and it is difficult to penetrate the flue gas, resulting in a slow cooling process of the mainstream flue gas, and the required cooling space is also correspondingly large; if there is insufficient space, the side-outlet flue gas is prone to tail swinging, and the tail-outlet flue gas temperature is often in the downstream of the viscosity range. In particular, the side-outlet flue gas duct is very easy to stick to ash and requires multiple air cannons to clear it, which will have a greater impact on the subsequent system. Summary of the invention

[0005] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art and propose a high-temperature flue gas cooling structure with a high content of low-melting-point salt suitable for an incinerator, taking into account both protecting the furnace wall and improving the cooling efficiency, so as to achieve the effect of rapid cooling and avoiding salt deposition on the furnace wall.

[0006] The technical solution of the present invention is: a high-temperature flue gas cooling structure with a high content of low-melting-point salt suitable for an incinerator, comprising a furnace cooling area structure, a cooling water spray gun and a combined spray pipe;

[0007] The furnace cooling area structure adopts a cylindrical contraction form, and the ratio of the inner diameter before and after contraction D / d is 1.25~1.5;

[0008] The combined nozzle includes a plurality of identical nozzles uniformly distributed circumferentially along the same height, and is arranged at a position D of 1 / 10 of the furnace inner diameter upstream of the contraction section of the furnace cooling area structure; the external cooling air is delivered to the combined nozzle, and the combined nozzle converts the static pressure of the cooling air into dynamic pressure, forming a jet in the direction of the ring wall and a jet biased toward the center of the furnace body. The two jets are in opposite directions, and the jet in the direction of the ring wall supports the jet biased toward the center of the furnace body. At the same time, the interaction between the two generates a local vortex to accelerate the mixing of the flue gas and the cooling air;

[0009] The cooling water spray gun is used to reduce the flue gas flow after cooling. It is set at the position D of 1 / 2 furnace inner diameter upstream of the combined nozzle. The spray gun inclination angle β is 5° to 15° downward, and the spray gun atomization angle is between 60° and 75°.

[0010] Furthermore, the contraction angle α of the furnace cooling area structure is 45 to 60 degrees.

[0011] Furthermore, the outlet height of the furnace cooling zone structure is 1 / 4 to 1 / 3 of the outlet diameter d.

[0012] Furthermore, the jet velocity in the direction of the annular wall and the jet velocity toward the center of the furnace body is not less than 35 m / s.

[0013] Furthermore, the number of nozzles of the combined nozzle must ensure that the jet coverage length in the annular wall direction multiplied by the number of nozzles is greater than the circumference of the furnace cross section, and the coverage length is the length at which the average jet velocity decays to 50%.

[0014] Furthermore, the ratio of the jet in the direction of the annular wall to the total cooling air flow is 0.35-0.45.

[0015] Furthermore, the jet design angle θ biased toward the center of the furnace body is selected to be 5° to 30°.

[0016] Furthermore, the external cooling air uses low-temperature circulating flue gas or normal temperature air, and the temperature of the low-temperature circulating flue gas is between 120°C and 180°C.

[0017] Furthermore, the heat absorbed by water cooling through the cooling water spray gun accounts for no more than 50%.

[0018] Furthermore, 3 to 4 cooling water spray guns are evenly arranged along the circumference at the same height.

[0019] The beneficial effects of the present invention compared with the prior art are:

[0020] The present invention can efficiently cool down the high-temperature salty flue gas within the designed area, and effectively protect the furnace wall to avoid the problem of salt adhesion or even blockage. Compared with similar products, it saves about 30% of space, and the outlet temperature is uniform, there is no risk of adhesion to the subsequent system, which is conducive to the long-term operation of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the assembly and working principle of the high-temperature flue gas cooling structure of the present invention;

[0022] Figure 2 It is a schematic diagram of jet distribution of the combined nozzle of the present invention;

[0023] Explanation of the reference numerals: 1 - furnace cooling area structure, 11 - inlet high-temperature salt-containing flue gas, 12 - outlet low-temperature salt-containing flue gas, 2 - cooling water spray gun, 3 - combined nozzle, 31 - annular wall jet, 32 - local vortex, 33 - eccentric jet. DETAILED DESCRIPTION

[0024] The present invention proposes a high-temperature flue gas cooling structure suitable for an incinerator with a high content of low-melting-point salt, which cools the high-salt high-temperature flue gas by cooling with normal temperature air or low-temperature circulating flue gas (hereinafter referred to as cooling air) or in combination with water cooling.

[0025] like Figure 1 As shown, the high-temperature flue gas cooling structure of the present invention includes three parts: a furnace cooling area structure 1, a cooling water spray gun 2 and a combined spray pipe 3.

[0026] The furnace cooling area structure 1 adopts a cylindrical contraction form, the contraction angle α can be 45 to 60 degrees, the ratio of the inner diameter before and after contraction D / d can be 1.25 to 1.5, and the outlet height h2 can be 1 / 4 to 1 / 3 of the outlet diameter d.

[0027] The combined nozzle 3 includes a plurality of identical nozzles, and a setting height h1 is 1 / 10 of the furnace inner diameter D upstream of the contraction section of the furnace cooling area structure 1, and all the nozzles are at the same horizontal height and are evenly distributed along the circumference.

[0028] The working principle of the combined nozzle 3 is as follows: the external cooling air is delivered to the combined nozzle 3 through the fan, and the combined nozzle 3 converts the static pressure of the cooling air into dynamic pressure, forming a jet in the direction of the annular wall, referred to as the annular wall jet 31, and a jet biased toward the center of the furnace body, referred to as the eccentric jet 33. The directions of the two jets are opposite, and the annular wall jet supports the eccentric jet. At the same time, the interaction between the two generates a local vortex 32 to accelerate the mixing of the flue gas and the cooling air. Figure 2 shown.

[0029] The combined nozzle 3 can also use low-temperature circulating flue gas instead of normal temperature air as cooling air, and the circulating flue gas temperature is between 120℃ and 180℃. Compared with using normal temperature air, low-temperature circulating flue gas can improve the thermal efficiency of waste heat recovery equipment and reduce the influence of external environmental temperature and humidity changes and dust and other factors; but it will also increase the size of downstream equipment; it can be selected according to process and economic conditions.

[0030] The design parameters of the combined nozzle 3 depend on the cooling process conditions: the number of nozzles of the combined nozzle 3 depends on the inner diameter D of the furnace body. Specifically, the number of nozzles should ensure that the coverage length of the wall jet 31 (the length at which the average jet velocity decays to 50%) multiplied by the number of nozzles is slightly larger than the circumference of the furnace cross section. The preferred number is 6 to 12. The larger the inner diameter D of the furnace body, the more the number. The higher the required cooling amount of the flue gas center, the more the number. The wall jet 31 accounts for about 0.35 to 0.45 of the total cooling air flow rate. If the required cooling amount of the flue gas center is low, a smaller value is taken; the design angle θ of the eccentric jet 33 can be selected from 5° to 30°. If the required cooling amount of the flue gas center is high, a smaller value is taken; the speed of the wall jet 31 and the eccentric jet 33 is recommended to be above 35m / s, and can be appropriately increased if the pressure conditions permit.

[0031] The present invention can use water cooling to assist in reducing the flow rate of the flue gas after cooling. Considering the need to control the water content in the flue gas, it is not recommended that the water cooling absorbs more than 50% of the heat.

[0032] The cooling water spray gun is set at a height h3 of about 1 / 2 of the furnace inner diameter D upstream of the combined nozzle 3. Due to the cross-sectional shape of the furnace body and the need to protect the wall, the number of spray guns should be minimized. It is recommended to have 3 to 4 spray guns at the same height. The spray gun inclination angle β can be 5° to 15° downward to improve the volume utilization efficiency. The spray gun atomization angle is recommended to be between 60° and 75°. The cooling area of ​​the flue gas by cooling water is mainly concentrated in the center of the flue gas flow, and there will be no high-viscosity salt temperature range near the wall.

[0033] The present invention will be further described below in conjunction with the embodiments.

[0034] Example 1

[0035] like Figure 1 , Figure 2 As shown, the high-temperature flue gas cooling structure of this embodiment includes three parts: a furnace cooling area structure 1, a cooling water spray gun 2 and a combined spray pipe 3.

[0036] The furnace cooling area structure 1 adopts a cylindrical contraction form, the contraction angle α is 60 degrees, the ratio of the inner diameter before and after contraction D / d is 1.5, and the outlet height h2 is 1 / 3 of the outlet diameter d.

[0037] The combined nozzle 3 is composed of 8 nozzles uniformly distributed circumferentially at the same height, and is arranged at a height h1 upstream of the contraction section of the furnace cooling area structure 1, where h1 is approximately 1 / 10 of the furnace inner diameter D.

[0038] The combined nozzle 3 converts the static pressure of the cooling air into dynamic pressure, and can emit a jet in the direction of the annular wall, referred to as the annular wall jet 31, and a jet biased toward the center of the furnace body, referred to as the eccentric jet 33. The two jets are in opposite directions, and the annular wall jet 31 supports the eccentric jet 33. At the same time, the two interact with each other to generate a local vortex 32 to accelerate the mixing of the flue gas and the cooling air.

[0039] The ratio of the wall jet 31 to the total cooling air flow is about 0.4, and a smaller value is selected when the required cooling amount of the smoke center is low; the design angle θ of the eccentric jet 33 is selected to be 15°, and a smaller value is selected when the required cooling amount of the smoke center is high. The speeds of the two jets are above 35m / s.

[0040] Water cooling is used to assist in reducing the flue gas flow after cooling, and the proportion of heat absorbed by water cooling does not exceed 50%.

[0041] The cooling water spray gun 2 is set at the upstream height h3 of the cooling air combination nozzle 3, which is about 1 / 2 of the furnace inner diameter D. There are 4 cooling water spray guns 2 at the same height, with an inclination angle β pointing downward by 10° and an atomization angle between 60° and 75°.

[0042] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

[0043] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. A high-temperature flue gas cooling structure suitable for an incinerator containing a high content of low melting point salt, characterized in that: It comprises a furnace cooling area structure (1), a cooling water spray gun (2) and a combined spray pipe (3); The furnace cooling area structure (1) adopts a cylindrical contraction form, and the ratio of the inner diameter before and after contraction D / d is 1.25 to 1.5; The combined nozzle (3) comprises a plurality of identical nozzles uniformly distributed in the circumferential direction along the same height, and is arranged at a position D 1 / 10 of the furnace inner diameter upstream of the contraction section of the furnace cooling area structure (1); external cooling air is delivered to the combined nozzle (3), and the combined nozzle (3) converts the static pressure of the cooling air into dynamic pressure, thereby forming a jet in the direction of the annular wall and a jet biased toward the center of the furnace body, the two jets having opposite directions, and the jet in the direction of the annular wall supports the jet biased toward the center of the furnace body, and the two interact with each other to generate a local vortex to accelerate the mixing of the flue gas and the cooling air; The cooling water spray gun (2) is used to reduce the flow rate of the flue gas after cooling. It is arranged at the position D of 1 / 2 of the furnace inner diameter upstream of the combined spray pipe (3). The spray gun inclination angle β is 5° to 15° downward, and the spray gun atomization angle is between 60° and 75°.

2. A high-temperature flue gas cooling structure with a high content of low melting point salt suitable for an incinerator according to claim 1, characterized in that: The contraction angle α of the furnace cooling zone structure (1) is 45 to 60 degrees.

3. A high-temperature flue gas cooling structure with a high content of low melting point salt suitable for an incinerator according to claim 1, characterized in that: The outlet height of the furnace cooling zone structure (1) is 1 / 4 to 1 / 3 of the outlet diameter d.

4. A high-temperature flue gas cooling structure with a high content of low melting point salt suitable for an incinerator according to claim 1, characterized in that: The jet velocity in the direction of the annular wall and the jet velocity toward the center of the furnace body shall not be less than 35m / s.

5. A high-temperature flue gas cooling structure with a high content of low melting point salt suitable for an incinerator according to claim 4, characterized in that: The number of nozzles of the combined nozzle (3) is such that the jet coverage length in the direction of the annular wall multiplied by the number of nozzles is greater than the circumference of the furnace cross section, wherein the coverage length is the length at which the average jet velocity decays to 50%.

6. A high-temperature flue gas cooling structure with a high content of low melting point salt suitable for an incinerator according to claim 1, characterized in that: The proportion of the jet in the direction of the annular wall to the total cooling air flow is 0.35 to 0.

45.

7. A high-temperature flue gas cooling structure with a high content of low melting point salt suitable for an incinerator according to claim 1, characterized in that: The jet design angle θ that is biased toward the center of the furnace body is selected to be 5° to 30°.

8. A high-temperature flue gas cooling structure with a high content of low melting point salt suitable for an incinerator according to claim 1, characterized in that: The external cooling air uses low-temperature circulating flue gas or normal temperature air, and the temperature of the low-temperature circulating flue gas is between 120℃ and 180℃.

9. A high-temperature flue gas cooling structure with a high content of low melting point salt suitable for an incinerator according to claim 1, characterized in that: The heat absorbed by the water cooling of the cooling water spray gun (2) accounts for no more than 50%.

10. A high-temperature flue gas cooling structure with a high content of low melting point salt suitable for an incinerator according to claim 1, characterized in that: Three to four cooling water spray guns (2) are evenly arranged in the circumferential direction at the same height.

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